Tumor Cell Budding Research Articles

High MEIS3 Expression Indicates a Poor Prognosis for Patients with Stage II/III Colorectal Cancer.

The Wnt/β-catenin signaling pathway plays crucial roles in tumor budding and the epithelial-mesenchymal transition (EMT). Myeloid ecotropic viral insertion site 3 (MEIS3)-a direct target of Wnt/β-catenin-promotes vagal neural crest cell migration into the gut tissue during development; however, its role in cancer progression remains unclear. In this study, the role of MEIS3 in colorectal cancer (CRC) progression was investigated. We analyzed the association between MEIS3 protein expression and the clinical stages of CRC patients, and the effect on tumor cell migration and invasion by wound healing and transwell assays. Finally, we analyzed the association between MEIS3 expression and the disease-free survival (DFS) and overall survival of CRC patients through Kaplan-Meier analysis. We found that MEIS3 expression was strongly associated with CRC progression and could be employed to assess DFS in postoperative patients. MEIS3-positive cells were mainly distributed in the growth front and tumor-stroma interface of the CRC tissues, which contain abundant EMT-active and tumor budding cells dominating cancer metastasis. Moreover, MEIS3 promoted CRC cell migration and invasion by regulating effectors including laminin subunit beta 1, matrix metalloprotein 2, and vimentin. MEIS3 protein expression increased with CRC progression according to the clinical stage, which could be used as a biomarker to stratify CRC patients. The 5-year DFS of MEIS3-high patients was poorer than that of MEIS3-low patients (40.6% vs. 61.7%; p < 0.0001). Moreover, the 5-year DFS of stage II patients with MEIS3-high expression (53.4%) was comparable to that of stage III patients with MEIS3-low expression (49.5%), while the 5-year DFS of MEIS3-high patients in stage III (30.9%) was comparable to that of stage IV patients (29.6%). This study showed that MEIS3 can promote cancer cell metastasis and thus may be a promising biomarker for higher rates of recurrence in postoperative patients with stage II/III CRC.

CYTOR Facilitates Formation of FOSL1 Phase Separation and Super Enhancers to Drive Metastasis of Tumor Budding Cells in Head and Neck Squamous Cell Carcinoma.

Tumor budding (TB)is a small tumor cell cluster with highly aggressive behavior located ahead of the invasive tumor front. However, the molecular and biological characteristics of TB and the regulatory mechanisms governing TB phenotypes remain unclear. This study reveals that TB exhibits a particular dynamic gene signature with stemness and partial epithelial-mesenchymal transition (p-EMT). Importantly, nuclear expression of CYTORis identified to be the key regulator governing stemness and the p-EMT phenotype of TB cells, and targeting CYTOR significantly inhibits TB formation, tumor growth and lymph node metastasis in head and neck squamous cell carcinoma (HNSCC). Mechanistically, CYTOR promotes tumorigenicity and metastasis of TB cells by facilitating the formation of FOSL1 phase-separated condensates to establish FOSL1-dependent super enhancers (SEs). Depletion of CYTOR leads to the disruption of FOSL1-dependent SEs, which results in the inactivation of cancer stemness and pro-metastatic genes. In turn, activation of FOSL1 promotes the transcription of CYTOR. These findings indicate that CYTOR is a super-lncRNA that controls the stemness and metastasis of TB cells through facilitating the formation of FOSL1 phase separation and SEs, which may be an attractive target for therapeutic interventions in HNSCC.

Endoscopic Treatment of T1 Colorectal Cancer.

Commonly accepted criteria for curative resection of T1 colorectal cancer include R0 resection with horizontal and vertical clear margins (R0), absence of lympho-vascular or vessel infiltration (L0, V0), a low to moderate histological grading (G1/2), low tumor cell budding, and limited (<1000 µm) infiltration into the submucosa. However, submucosal infiltration depth in the absence of other high-risk features has recently been questioned as a high-risk situation for lymph-node metastasis. Consequently, endoscopic resection techniques should focus on the acquisition of qualitatively and quantitively sufficient submucosal tissue. Here, we summarize the current literature on lymph-node metastasis risk after endoscopic resection of T1 colorectal cancer. Moreover, we discuss different endoscopic resection techniques with respect to the quality of the resected specimen.

Abstract 1018: Multiplex immunofluorescence and image analysis to investigate the role of the immune contexture and fibroblast activation for tumor cell budding in colorectal cancer

Abstract The advent of immune oncology had a significant impact on the stratification of cancer patients in the past few years. Furthermore, immune cell phenotyping of the tumor microenvironment is becoming a tool not only for the identification of novel predictive biomarkers for cancer immunotherapy, but also for prognostic markers that may help to understand several mechanisms like invasion and epithelial-mesenchymal transition (EMT). We demonstrate how multiplexed immunofluorescence (mIF) assays and digital image analysis helped to investigate tumor budding in colorectal cancer by evaluating the tumor microenvironment and activated fibroblasts. Akoya Bioscience’s Opal detection system and fluorophores were optimized on LEICA Bond RX for use with human normal tonsil control tissues and FFPE colorectal cancer specimens. The 6-plex mIF panel included CD4 (clone SP35), CD8 (clone C8/144B), CD68 (clone PG-M1), FoxP3 (clone SP97), PD-L1 (clone SP263) and pan-Cytokeratin (clones AE1/AE3). In addition, FAP-alpha single-plex IHC was used to investigate reactivity of the stroma surrounding tumor cell buds. Each single marker of the mIF panel was independently validated for specificity regarding stripping efficacy and epitope stability, and for accuracy compared to single plex bright field immunohistochemistry. Automated image analysis and cellular phenotyping followed a workflow of custom Visiopharm apps. The tissue was segmented into regions of interest, such as areas with and without tumor cell budding, and bud microenvironment. Additional parameters like MSI (Microsatellite Instability) status and TNM classification were also taken into consideration for data analysis. The applied mIF immune cell panel and automated image analysis workflow identified a broad number of different immune cell phenotypes, including rare double- or triple-positive cell subtypes, as well as their spatial relation to tumor cell buds within the activated stroma region. This revealed new insights into the complexity of the tumor microenvironment in colorectal cancer around tumor cell buds, suggesting a potential effect of both the immune system and the stromal cells on tumor cell invasion into the surrounding tissue. Citation Format: Dirk Zielinski, Rebekka Vogtmann, Anne Siemon, Christina Koppel, Christina Schipper, Anastasiia Tereshchenko, Suso Platero, Hans-Ulrich Schildhaus. Multiplex immunofluorescence and image analysis to investigate the role of the immune contexture and fibroblast activation for tumor cell budding in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1018.

Evaluation of the Cellular Dissociation Grading, Based on Tumor Budding and Cell Nest Size, in Squamous Cell Carcinoma of the Penis.

Simple SummaryThe pathological status of regional lymph nodes (pN) is the most important predictor of survival in patients with invasive squamous cell carcinoma of the penis. However, staging strategies have limited prediction, which results in false-negative findings or unnecessary lymphadenectomies. Therefore, additional criteria should be identified to improve the prediction of lymph node involvement. The “Cellular Dissociation Grade” (CDG) is based on tumor cell budding and cell nest size. Many studies have examined the CDG in squamous cell carcinomas of other organs such as the lungs, oral cavity, pharynx, larynx, cervix and esophagus. In this study, the CDG was examined in 109 cases of invasive penile squamous cell carcinoma that were treated at the University Medicine Rostock between 2014 and 2022. Furthermore, its correlation with the pathologic status of regional lymph nodes (pN) as the main prognostic factor was verified. Finally, cellular dissociation grading was compared with classic WHO grading. The results showed that pN in penile squamous cell carcinoma showed a highly significant association with the CDG and no statistically significant association with WHO grading. These results support the notion that cellular dissociation grading is an important prognostic factor for squamous cell carcinoma.

Invasion-Associated Reorganization of Laminin 332 in Oral Squamous Cell Carcinomas: The Role of the Laminin γ2 Chain in Tumor Biology, Diagnosis, and Therapy.

Simple SummaryThe destructive growth of carcinomas is associated with crossing the border between the epithelial and the connective tissue parts of an organ. One component of this borderline, the basement membrane, is the heterotrimeric laminin 332, which mediates the adhesion of basal epithelial cells. This protein, in particular its gamma 2 chain, is fundamentally reorganized during tumor cell invasion. Specific deposition patterns of laminin 332 are also present in oral squamous cell carcinomas and have been shown to be of high diagnostic and predictive value. Furthermore, laminin 332 restructuring is associated with important tumor biological processes, e.g., stromal activation, the development of a motile phenotype, and tumor spreading. In this review, current knowledge in the field is summarized and the recommendation to consider laminin 332 as a promising grading and monitoring parameter and as a potential therapeutic target is discussed.Invasion of the connective tissue by carcinoma cells is accompanied by disintegration and reorganization of the hemidesmosomes, which connect the basement membrane to the basal epithelial cells. In terms of mediating the basement membrane, i.e., basal cell interactions, the heterotrimeric laminin 332 is the most important bridging molecule. Due to this distinct function, laminin 332, especially its gamma 2 chain, came into the focus of cancer research. Specific de novo synthesis and deposition patterns of laminin 332 are evident upon development and progression of oral squamous cell carcinomas (OSCCs). Loss from the basement membrane, cytoplasmic accumulation, and extracellular deposition are associated with crucial processes such as stromal activation and immune response, epithelial to mesenchymal transition, and tumor cell budding. In networks with components of the tumor microenvironment, altered expression of laminin 332 chains, proteolytic processing, and interaction with integrin receptors seem to promote cancer cell migration. Indeed, reorganization patterns are shown to have a high diagnostic and prognostic value. Here, we summarize the current knowledge on laminin 332 reorganization in OSCCs with special focus on its gamma 2 chain and provide, based on the current literature, evidence on its promising role as a grading and monitoring parameter and as a potential therapeutic target.

Tumor cell budding as a prognostic and potentially therapeutically targetable biomarker in head and neck cancer.

6053 Background: Several studies have demonstrated a negative prognostic impact of tumor cell budding (TCB) in HPV- head and neck squamous cell carcinoma (HNSCC), but analyses of its prognostic impact in HPV+ HNSCC and of the underlying molecular alterations are lacking. Methods: The study cohort included 331 HPV- and HPV+ HNSCC from TCGA with digitalized H&amp;E-stained slides available. Corresponding mutation, methylation, and gene expression data were obtained from the pan-cancer atlas web page. Tumor buds were defined as clusters of up to four tumor cells separated from the tumor mass. The numbers of tumor buds were evaluated in ten digital high-power fields by a senior pathologist. A two-tier cellular dissociation grading system was introduced by separating tumors with six or more tumor buds (TCB-high) from tumors with fewer tumor buds (TCB-low). The impact of TCB on overall survival (OS) was analyzed using Cox proportional hazard models. Results with p &lt; 0.05 were considered significant. Association of TCB with mutations was analyzed using the Wilcoxon test. Association of TCB with gene expression and methylation was analyzed using Spearman correlations. Lists of altered genes were compiled correcting the p-values with the Benjamin-Hochberg method and controlling the FDR at 5%. Results: In a univariate analysis, OS was significantly shorter in TCB-high tumors compared to TCB-low tumors in HPV- HNSCC (HR = 1.4, 95% CI 1.0-2.3) and HPV+ HNSCC (HR = 5.0, 95% CI 1.9-13.7). Shorter OS in TCB-high HNSCC was confirmed in a multivariate analysis including age, sex, HPV status, tumor site, tumors stage, and tumor margin status (HR = 1.7, 95% CI 1.2-2.4). Significant association of TCB with mutations was detected for two genes: NSD1 mutations correlated negatively with TCB in HPV- HNSCC, while TP53 mutations correlated positively with TCB in HPV+ HNSCC. Methylation of 126 (1%) genes was associated with TCB in HPV- HNSCC, while methylation of 511 (3%) genes was associated with TCB in HPV+ HNSCC. Expression of 422 (2%) genes was associated with TCB in HPV- HNSCC, while expression of 786 (4%) genes was associated with TCB in HPV+ HNSCC. Among these genes, those annotated to the epithelial mesenchymal transition were highly significantly enriched in both HPV- HNSCC (5.5-fold enrichment) and HPV+ HNSCC (2.7-fold enrichment). Conclusions: Evaluation of TCB based on digital HE slides was conducted in a large clinically and molecularly characterized HNSCC cohort. The prognostic impact of TCB could be validated in HPV- HNSCC, while a prognostic impact of TCB could be demonstrated for the first time in HPV+ HNSCC. TCB correlated with mutations of only two genes and theses correlations were imperfect. A plethora of genes correlated with TCB on the level of methylation and gene expression level. These genes should be further analyzed and prioritized for the evaluation of therapeutic targeting.

Tumor cell budding in preoperative biopsies of esophageal and gastroesophageal junction carcinoma independently predicts survival in a grade-dependent manner

BackgroundTumor budding is a prognostic factor in biopsies of different tumor entities. Recent evidence suggests that this also applies to esophageal squamous cell carcinomas. Since esophageal cancer is diagnosed by biopsy, the aim of this study was to investigate whether tumor budding in pretherapeutic biopsies of a mixed tumor population of the esophagus and gastroesophageal junction might predict survival. MethodsIn this retrospective analysis, samples of 78 patients were analyzed (55 adenocarcinomas, 17 squamous cell carcinomas, 5 adenosquamous carcinomas, 1 carcinosarcoma). In addition to preoperative biopsies, budding foci in corresponding resection specimens were assessed and related to overall and relapse-free survival. ResultsThe main finding was that the number of budding foci in preoperative biopsies predicted overall survival independent of the patient’s age and disease stage in a grade-specific (P = .009) manner. In patients with grade 2 tumors, each additional budding focus was associated with an increased chance of death by a factor of 1.28 (hazard ratio 95% confidence interval 1.06–1.55, P = .011). There was no significant association between survival and the number of budding foci in patients with grade 3 tumors, and no budding was observed in grade 1 tumors. Budding foci in resection specimens also showed a certain association with survival, but to a lesser degree. ConclusionBudding foci in preoperative biopsies might serve to improve prognostic accuracy in esophageal carcinomas.

Molecular landscape of vulvovaginal squamous cell carcinoma: new insights into molecular mechanisms of HPV-associated and HPV-independent squamous cell carcinoma

Squamous cell carcinomas of the lower female genital tract may be human papillomavirus-associated or independent. We studied the HPV status, mutational repertoire, histology, and clinical data of 28 samples from 26 patients, 65% with a vulvar primary and 35% with a vaginal primary. These represented invasive vulvovaginal squamous cell carcinomas that underwent clinical tumor-normal targeted massively parallel sequencing analysis. HPV status was determined using the HPV high-risk RNA ISH assay and/or by MSK-IMPACT. Eleven patients had HPV-associated squamous cell carcinoma (four vulvar and seven vaginal) and 15 patients had HPV-independent SqCC (13 vulvar and 2 vaginal). Well-differentiated squamous cell carcinomas were always HPV-independent. HPV-independent moderately and poorly differentiated carcinomas frequently had alterations in the NOTCH signaling pathway (6/7), which were also associated with increased tumor budding (P: 0.002). HPV-associated vulvovaginal squamous cell carcinoma had PIK3CA activating mutations (7/11, 64%) as the most common genomic event, while TERT gene alterations, mainly TERT promoter mutations (14/15 cases, 93%) featured significantly in HPV-independent carcinomas. Other common abnormalities in HPV-independent tumors were TP53 mutations (13/15, 87%), CDKN2A alterations (10/15, 67%), and NOTCH1 and FAT1 mutations (7/15, 47% each). A subset of both HPV-associated and -independent tumors had NOTCH pathway alterations (6/11, 55% and 10/15, 67% respectively), but different genes in this pathway were altered in these tumors. In summary, TERT, TP53, CDKN2A, and NOTCH1 gene alterations strongly point away from an HPV-driven process (odds ratios: 0.01, 0.07, 0, and 0, respectively with p values < 0.02 for all four genes), while PIK3CA activating mutations without the other mutations strongly favors an HPV-driven tumor (odds ratio: 10.12, p value: 0.016). HPV-independent carcinomas are more likely to be moderately-poorly differentiated with intermediate to high tumor cell budding. Cancer cell fraction analysis of HPV-independent squamous carcinomas suggests that TERT and/or NOTCH1 alterations along with TP53 alterations can be the initiating event in these tumors.

Evaluation of the Relationship Between the Invasive Front of Oral Squamous Cell Carcinoma and Clinicopathological Parameters.

Background & Objective:The present study investigated the relationship between invasive front (IF) of tumors and clinicopathological parameters including stage, grade, nodal involvement, lymphocytic host response (LHR), recurrence, overall survival (OS), and disease-free survival (DFS).Methods:A total of 87 oral squamous cell carcinoma (OSCC) biopsies were evaluated. Clinical stage, grading, nodal involvement, time of recurrence, OS, and DFS were assessed. The number of tumor budding cells in the IF was measured by two pathologists with an optic microscope. IF was graded to low risk (<5) and high risk (>5), according to the counting of tumor budding as a single cancer cell or cluster cells. Also, LHR was reported in the IF as mild, moderate, and severe.Results:IF was reported in 43.7% of patients as a low-risk group and 49.4% as a high-risk group. LHR was also mild in 31%, moderate in 25.3%, and severe in 43.7% of the patients. Most of the patients were in stage IV (31%) and grade 1 (60.9%). The high risk IF group had a significant statistical relationship with stage (P=0.001), grade (P=0.039), five years OS (P=0.03), five years DSF (P=0.01), and lymph node involvement (P=0.007). The relation between LHR and stage of disease was significant (P=0.034).Conclusion:Considering the essential role of histopathological reports in the treatment plan of patients and the relationship between IF and clinical parameters, IF evaluation in routine histopathological examinations, especially in the early stages of OSCC, seems to be necessary.

Evaluating the Histologic Grade of Digital Squamous Cell Carcinomas in Dogs with Dark and Light Haircoat—A Comparative Study of the Invasive Front and Tumor Cell Budding Systems

Simple SummaryThis study compares two different adapted grading systems for Canine digital squamous cells carcinomas, taking into account the animals’ haircoat color and focusing on the tumor’s invasive front. In general, dark-haired breeds develop more poorly differentiated DSCC than their light-haired counterparts. Additionally, both grading systems challenged are in agreement when grading well differentiated CDSCC in both populations but are discordant when assessing tumors with poorly differentiated features. To our knowledge, this is the first study comparing CDSCC in dogs by two histological grading systems, taking into account their phenotypical and presumed genotypical haircoat color and demonstrating that digital squamous carcinomas are not only more common in dark-haired dogs, but potentially more aggressive.Canine digital squamous cell carcinomas (CDSCC) are particularly aggressive when compared to their occurrence in other locations. Although these neoplasms are more frequently seen in dark-haired dogs, such as Giant Schnauzers, there are no data checking whether these tumors are histologically different between breeds. We histologically evaluated DSCC from 94 dogs. These were divided into two groups, namely, (1) dark-haired (N = 76) and (2) light-haired breeds (N = 18), further subdividing Group 1 into three subgroups, (1a) black breeds (n = 11), (1b) Schnauzers (n = 34) and (1c) black & tan breeds (n = 31). Adaptations from two different squamous cell carcinomas grading schemes from human and veterinary literature were used. Both systems showed significant differences when compared to Groups 1 and 2 in terms of final grade, invasive front keratinization, degree of invasion, nuclear pleomorphism, tumor cell budding, smallest tumor nest size and amount of tumor stroma. Group 2 was consistently better differentiated CDSCC than Group 1. However, there were no significant differences among the dark-haired breeds in any of the features evaluated. This study represents the first attempt to grade CDSCC while taking into account both phenotypical and presumptive genotypical haircoat color. In conclusion, CDSCC are not only more common in dark-haired dogs, they are also histologically more aggressive.

Podoplanin is an efficient predictor of neck lymph node metastasis in tongue squamous cell carcinoma with low tumor budding grade.

The current study investigated the efficacy of podoplanin expression in tumor budding cells as a predictor of neck lymph node metastasis (NLM) in patients with tongue squamous cell carcinoma (SCC) of low tumor budding grade (TBG). A total of 99 patients with early T-stage tongue SCC of any clinical N status who received the initial curative treatment were enrolled. The association between podoplanin expression and NLM was immunohistochemically analyzed, with a focus on tongue SCC with low TBG. The disease-specific survival (DSS) rate was 77% at 5 years, and a significant difference was observed between the NLM-positive and NLM-negative groups, and between the low (n=77) and high (n=22) TBG groups. In the low TBG group, there was a significant difference in DSS between the NLM-positive and NLM-negative groups. The multivariate analysis showed that lymphatic vessel invasion (ly) [odds ratio (OR)=11.5, 95% confidence interval (CI): 1.50–87.6; P=0.02] and podoplanin expression (OR=7.07, 95% CI: 1.80–27.7; P=0.005) were significantly correlated with NLM. Furthermore, negative predictive values (NPV) of ly and podoplanin expression for NLM were 75% and 88%, respectively. Considering the balance of stratification case number adding to ratio, NLM-negative prediction by podoplanin was more significant than that by ly for the low TBG group. The results of the present study demonstrated that podoplanin expression in tumor budding is an independent and efficient predictor of NLM in the tongue SCC with low TBG. The low TBG and podoplanin-negative cases may be candidates for the wait and watch policy, therefore, reducing inappropriate elective neck lymph node dissections.

Worst pattern of invasion - type 4 (WPOI-4) and Lymphocyte host response should be mandatory reporting criteria for oral cavity squamous cell carcinoma: A re-look at the American Joint Committee of Cancer (AJCC) minimum dataset.

A proportion of early-stage node-negative oral squamous carcinoma patients fail despite complete surgical resection. Adjuvant treatment in early oral cancer is controversial and is often individualized based on stage, depth, and margin status. We reviewed various histological markers in pT1/T2N0 cases, resected upfront with elective nodal dissection, with an emphasis on tumor-tissue interface characteristics of the worst pattern of invasion (WPOI), tumor cell nest size (sCNS), budding and lymphocytic host response (LHR), to assess their prognostic significance. Archived blocks of 95 cases were reviewed. Tumor stage, grade, size, depth of invasion, lymphovascular, and perineural invasion, WPOI, LHR, sCNS, and tumor bud (single cells or <5 cell clusters) score were recorded. Prognostic significance was statistically analyzed using SPSS software version 20. Depth of invasion (P = 0.008), WPOI- 4 and 5 (P = 0.033), sCNS (<5 cells) at tumor interface (P = 0.010), high bud count (≥3 buds/40 × hpf) (P = 0.021) and poor LHR (P = 0.019) correlated significantly with poor disease-free survival on univariate analysis. However, on multivariate analysis only LHR and WPOI-4 (that is presence of small cell nests or buds) were significant, with high hazard ratio of 4.351 (95% CI 1.290-14.676, P = 0.018) and 5.019 (95% CI 1.212-20.789, P = 0.026), respectively. We propose mandatory reporting of WPOI-4 at the tumor interface and absence of LHR, as significant markers of poor prognosis in early-stage oral cavity squamous carcinoma.

MiR-21 expression analysis in budding colon cancer cells by confocal slide scanning microscopy

MicroRNA-21 (miR-21) expression in stromal fibroblastic cells in colorectal cancer is well-documented, whereas miR-21 expression in tumor budding cells (TBCs) is poorly described. TBCs are locally invasive carcinoma cells with increased metastatic properties and characteristics of epithelial to mesenchymal transition. This study was conducted to better characterize the expression of miR-21 in TBCs. First, chromogenic miR-21 in situ hybridization (ISH) staining was performed in 58 colon adenocarcinomas with evident TBCs. Then, to obtain unambiguous identification of miR-21 in the TBCs, twenty cases were selected for an additional multiplex fluorescence analysis combining miR-21 ISH with cytokeratin and laminin-5γ2 immunofluorescence. Employing confocal slide scanning microscopy, comprehensive digital images of the invasive front (10–40 mm2) were obtained from 16 of the 20 cases, and miR-21 expression was evaluated in cytokeratin-positive TBCs. The high resolution of the confocal digital slide images allowed a detailed examination of the confocal stacks of the multiplex-stained tissue sections. The cases with the highest fraction of miR-21 positive TBCs were all stage III cancers defined by the presence of regional lymph node metastasis. Some of the miR-21 positive TBCs were also laminin-5γ2 positive. The confocal image stacks also revealed that some TBCs were actually directly connected to malignant glands. In conclusion, miR-21 expression was unambiguously identified in TBCs by evaluation of digital slides obtained by confocal slide scanning microscopy. In addition, the digital confocal slides provided a more detailed understanding of local cancer cell invasion by allowing evaluation of the cell structures in three dimensions.

Digital image analysis of pan-cytokeratin stained tumor slides for evaluation of tumor budding in pT1/pT2 colorectal cancer: Results of a feasibility study

Tumor budding is an independent prognostic factor in colorectal cancer. However, varying degrees of interobserver agreement and reproducibility challenges the use of tumor budding in diagnostics. Immunohistochemical staining of tumor slides with pan-cytokeratin visualizes the budding tumor cells and has been suggested to improve reproducibility. Here we demonstrate the methodology of tumor budding assessment using digital image analysis based on tumor slides stained for pan-cytokeratin, and investigate interobserver agreement, agreement between manual and digital assessment methods and digital reproducibility between users.Tumor slides from 126 patients with pT1/pT2 colorectal cancer were stained with pan-cytokeratin and tumor budding at the invasive tumor front was assessed by conventional manual microscopy. A digital image analysis algorithm for identification and quantification of budding tumor cells was developed and tested on the pan-cytokeratin stained slides.Manual assessment of tumor budding using pan-cytokeratin stained tumor slides exhibited high correlations (Spearman Rank 0.84-0.89, p < 0.001),excellent agreement between observers (Intra-class correlation coefficient (ICC): 0.86 -0.87) and 2.20 higher odds for regional metastases with increasing budding counts (p = 0.017). Digital image analysis correlated well to manual assessment (Spearman Rank 0.71-0.88) and agreement between the two methods was good (ICC 0.62-0.82). However, only a trend towards increased odds for metastatic progression was found for the adjusted digital estimates (p = 0.076). Digital estimates were higher than manual estimates, demonstrated by a systematic median difference of 3–4.5 buds. Image analysis was highly reproducible between users of the algorithm (ICC 0.98). In conclusion, assessment of tumor budding using pan-cytokeratin stained tumor slides is a method with high correlation and agreement between observers. Digital image analysis quantifies budding tumor cells in high agreement with manual estimates, but approval of the digital slides by a pathologist is mandatory. The method qualifies for further investigation.

Abstract 475: Characterization of miR-21 expression in budding colon cancer cells using digital images of multiplex fluorescence stained slides obtained by confocal scanning microscopy

Abstract This study was undertaken to analyze the presence and prevalence of microRNA-21 (miR-21) positive budding cancer cells in colon cancer using confocal scanning microscopy. Budding cancer cells are locally invasive cancer cells with increased metastatic properties and characteristics of epithelial to mesenchymal transition (EMT). Expression of miR-21 in stromal fibroblastic cells in colorectal cancers is well documented (1,2), whereas miR-21 expression in budding cells is poorly described. In order to characterize miR-21 positive budding cells, we first developed a multiplex fluorescence staining method by combining miR-21 in situ hybridization with immunohistochemical staining for cytokeratin and budding cell marker laminin-γ2, and stained 16 colon cancer cases (stage II, n=5, stage III, n=11). We then employed a confocal scanning microscope to obtain 15-55 GB digital images covering areas of 10-40 mm2 of the invasive front. The high resolution of the confocal digital images allowed detailed examination of the 4-fluorophore-stained slides using extended focus and z-stack images, e.g. in the discrimination of epithelial cells from adjacent stromal cells. All cytokeratin-positive budding cells were evaluated for the presence of miR-21 and laminin-γ2. Five out of the 16 cases had more than 10% miR-21 positive budding cells, a few of which were also laminin-γ2 positive. All five cases were stage III cancers. The presence of miR-21 in the budding cancer cells was not associated with the level of tumor budding. These observations suggest that the miR-21 expression in tumor budding cells increases with the progression of the cancer and is independent of laminin-γ2.

Deletions at SLC18A1 increased the risk of CRC and lower SLC18A1 expression associated with poor CRC outcome.

Copy number variations (CNVs) contribute to the development of colorectal cancer (CRC). We conducted a two-stage association study to identify CNV risk loci for CRC. We performed a gene-based rare CNV study on 694 sporadic CRC and 1641 controls using Illumina Human-OmniExpress-12v1.0 BeadChips, and further replicated in 934 CRC cases and 2680 controls for risk CNVs by using TaqMan Copy Number Assay. Tumor buddings, cancer cells in the center of primary tumor and normal intestinal epithelial cells were captured using laser capture microdissection (LCM) and were assayed using AffymetrixGeneChip® Human Genome U133 Plus 2.0 Array. In addition, The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus data were assessed for the effects of risk CNVs. We found that germline deletions affecting the last six exons of SLC18A1 significantly associated with CRC with a combined P value of 6.4 × 10-5 by a two-stage analysis. Both in TCGA CRC RNA seq dataset and GDS4382, SLC18A1 was significantly down regulated in CRC tissues than in paired normal tissues (N = 32 and 17 pairs, P = 0.004 and 0.009, respectively). In LCM samples, similar observations were obtained that the expression levels of SLC18A1 in the tumor buddings, cancer cells in the center of primary tumor, and stroma of both tumor budding and cancer cells were lower than normal intestinal epithelial and stromal cells (fold change = 0.17-0.62, 0.12-0.57 and 0.37-0.68, respectively). In summary, the germline deletions at SLC18A1 contributed to the development of CRC. The role of SLC18A1 required further exploration.

MicroRNA-200b is downregulated in colon cancer budding cells.

BackgroundThe microRNA-200 (miR-200) family acts as a major suppressor of epithelial-mesenchymal transition (EMT). Impaired miR-200 expression may lead to EMT initiation and eventually cancer dissemination. The presence of tumor budding cells (TBC) is associated with metastasis and poor prognosis, and molecular similarities to EMT indicate that these cells may reflect ongoing EMT. The aim of this study was to investigate the expression of miR-200b in budding cells of colon cancer and the relationship with the EMT-markers E-cadherin, β-catenin and laminin-5γ2.Material & methodsMiR-200b was investigated by in situ hybridization in 58 cases of stage II (n = 36) and III colon (n = 22) cancers with tumor budding. Expression of E-cadherin, β-catenin and laminin-5γ2 was examined by immunohistochemistry. A multiplex fluorescence assay combining miR-200b with cytokeratin and laminin-5γ2 was employed on a subset of 16 samples.ResultsMiR-200b was downregulated in the TBC at the invasive front of 41 out of 58 (71%) cases. The decline was present in both mismatch satellite stable and instable adenocarcinomas. The majority of cases also showed loss of membranous E-cadherin and increased nuclear β-catenin in the TBC, while laminin-5γ2 expression was upregulated at the invasive front and in the tumor buds of approximately half the adenocarcinomas. However, the miR-200b decline was not statistically associated with the expression of any of the EMT-markers. The miR-200b decline was also documented by multiplex fluorescence. Fourteen out of fifteen cases showed a decrease in miR-200b expression in the majority of the TBC, but no obvious relationship between miR-200b and laminin-5γ2 expression was observed. Conclusion: The findings support the assumption of a miR-200b related downregulation in colon cancer budding cells. Whether miR-200b expression may be of clinical significance awaits further studies.

Expression profiling of budding cells in colorectal cancer reveals an EMT-like phenotype and molecular subtype switching

Background:Tumour budding, described as the presence of single cells or small clusters of up to five tumour cells at the invasive margin, is established as a prognostic marker in colorectal carcinoma. In the present study, we aimed to investigate the molecular signature of tumour budding cells and the corresponding tumour bulk.Methods:Tumour bulk and budding areas were microdissected and processed for RNA-sequencing. As little RNA was obtained from budding cells, a special low-input mRNA library preparation protocol was used. Gene expression profiles of budding as compared with tumour bulk were investigated for established EMT signatures, consensus molecular subtype (CMS), gene set enrichment and pathway analysis.Results:A total of 296 genes were differentially expressed with an FDR <0.05 and a twofold change between tumour bulk and budding regions. Genes that were upregulated in the budding signature were mainly involved in cell migration and survival while downregulated genes were important for cell proliferation. Supervised clustering according to an established EMT gene signature categorised budding regions as EMT-positive, whereas tumour bulk was considered EMT-negative. Furthermore, a shift from CMS2 (epithelial) to CMS4 (mesenchymal) was observed as tumour cells transit from the tumour bulk to the budding regions.Conclusions:Tumour budding regions are characterised by a phenotype switch compared with the tumour bulk, involving the acquisition of migratory characteristics and a decrease in cell proliferation. In particular, most tumour budding signatures were EMT-positive and switched from an epithelial subtype (CMS2) in the tumour bulk to a mesenchymal subtype (CMS4) in budding cells.

A Novel High-Throughput 3D Screening System for EMT Inhibitors: A Pilot Screening Discovered the EMT Inhibitory Activity of CDK2 Inhibitor SU9516.

Epithelial-mesenchymal transition (EMT) is a crucial pathological event in cancer, particularly in tumor cell budding and metastasis. Therefore, control of EMT can represent a novel therapeutic strategy in cancer. Here, we introduce an innovative three-dimensional (3D) high-throughput screening (HTS) system that leads to an identification of EMT inhibitors. For the establishment of the novel 3D-HTS system, we chose NanoCulture Plates (NCP) that provided a gel-free micro-patterned scaffold for cells and were independent of other spheroid formation systems using soft-agar. In the NCP-based 3D cell culture system, A549 lung cancer cells migrated, gathered, and then formed multiple spheroids within 7 days. Live cell imaging experiments showed that an established EMT-inducer TGF-β promoted peripheral cells around the core of spheroids to acquire mesenchymal spindle shapes, loss of intercellular adhesion, and migration from the spheroids. Along with such morphological change, EMT-related gene expression signatures were altered, particularly alteration of mRNA levels of ECAD/CDH1, NCAD/CDH2, VIM and ZEB1/TCF8. These EMT-related phenotypic changes were blocked by SB431542, a TGF-βreceptor I (TGFβR1) inhibitor. Inside of the spheroids were highly hypoxic; in contrast, spheroid-derived peripheral migrating cells were normoxic, revealed by visualization and quantification using Hypoxia Probe. Thus, TGF-β-triggered EMT caused spheroid hypoplasia and loss of hypoxia. Spheroid EMT inhibitory (SEMTIN) activity of SB431542 was calculated from fluorescence intensities of the Hypoxia Probe, and then was utilized in a drug screening of EMT-inhibitory small molecule compounds. In a pilot screening, 9 of 1,330 compounds were above the thresholds of the SEMTIN activity and cell viability. Finally, two compounds SB-525334 and SU9516 showed SEMTIN activities in a dose dependent manner. SB-525334 was a known TGFβR1 inhibitor. SU9516 was a cyclin-dependent kinase 2 (CDK2) inhibitor, which we showed also had an EMT-inhibitory activity. The half maximal inhibitory concentration (IC50) of SB-525334 and SU9516 were 0.31 μM and 1.21 μM, respectively, while IC50 of SB431542 was 2.38 μM. Taken together, it was shown that this 3D NCP-based HTS system was useful for screening of EMT-regulatory drugs.